Transcript Forensic Toxicology found in Postmortem

Chapter 6
FORENSIC TOXICOLOGY
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-1
Toxicology
Toxicology—the study of the adverse
effects of chemicals or physical agents
on living organisms. Video
Types:
Environmental—air, water, soil
Consumer—foods, cosmetics, drugs
Medical, clinical, forensic
2
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-2
Toxicologists
• Toxicologists are charged with the
responsibility for detecting and identifying the
presence of drugs and poisons in body fluids,
tissues, and organs. Video
• Toxicologists not only work in crime
laboratories and medical examiners’ offices,
but may also reach into hospital laboratories
and health facilities to identify a drug overdose
or monitor the intake of drugs. Careers video
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-3
Mathieu Orfilia – Father of Tox
• The father of toxicology was Mathieu
Orfilia in the early 1800’s .
• His work mainly centered around
arsenic.
• It was relatively easy to get because it
was the rat poison of the day and was the
favorite murder weapon among poor
people.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-4
Intoxicant vs. Poison:
• An intoxicant such as alcohol requires
that a relatively large amount be added
to be lethal.
• A poison, like cyanide, requires a
relatively small amount to be fatal.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-5
Forensic Toxicology found in
Postmortem—medical examiner or coroner
Criminal—motor vehicle accidents (MVA)
Workplace—drug testing
Sports—human and animals
Environment—industrial, catastrophic,
terrorism. Video link
6
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-6
Environmental Example:
Love Canal New York
An example of where forensic toxicology
impacts the population is the Love Canal
Disaster. Video
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-7
Toxicology
Toxic substances may:
*Be a cause of death
*Contribute to death
*Cause impairment
*Explain behavior
8
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-8
Life Example: Carbon Monoxide:
Video Link
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-9
Aspects of Toxicity
Dosage
The chemical or physical form of the
substance
The mode of entry into the body
Body weight and physiological conditions
of the victim, including age and sex
The time period of exposure
The presence of other chemicals in the
body or in the dose
10
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-10
Lethal Dose
LD50 refers to the dose of a substance
that kills half the test population,
usually within four hours. Testing is
usually done on animals that compare
well to humans metabolism.
Expressed in milligrams of substance
per kilogram of body weight
11
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-11
Toxicity Classification
LD50 (rat,oral)
Correlation to Ingestion
by 150-lb Adult Human
Toxicity
<1 mg/kg
a taste to a drop
extreme
1–50 mg/kg
to a teaspoon
high
50–500 mg/kg
to an ounce
moderate
500–5,000 mg/kg
to a pint
slight
5–15 g/kg
to a quart
practically nontoxic
Over 15 g/kg
more than 1 quart
relatively harmless
12
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-12
Symptoms of Various Types of Poisoning
Type of Poison
1. Caustic poison (lye) Characteristic burns around the
lips and mouth of victim
2. Carbon monoxide Red or pink patches on the chest
and thigh, unusually bright red lividity
3. Sulfuric acid Black vomit
4. Hydrochloric acid Greenish-brown vomit
5. Cyanide- Seizures, Burnt almond odor
6. Arsenic diarrhea, vomiting, blood in the urine,
cramping muscles, stomach pain, and convulsions.
7. Methyl (wood) or isopropyl (rubbing) alcohol Nausea
and vomiting, unconsciousness possibly blindness
13
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-13
To Prove a Case
Prove a crime was committed
Motive
Intent
Access to poison
Access to victim
Death was homicidal
Death was caused by poison
14
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-14
Alcohol—Ethyl Alcohol (C2H5OH)
Most abused drug in America
About 40 percent of all traffic deaths are
alcohol-related. Acts as a depressant
Toxic—affecting the central nervous
system, especially the brain
Colorless liquid, generally diluted in water
Alcohol appears in blood within minutes;
30–90 minutes for full absorption
Detoxification—about 90 percent in the15
liver
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-15
Introduction
• A major branch of
forensic toxicology
deals with the
measurement of
alcohol in the body for
matters that pertain to
violations of criminal
law.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
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Rate of Absorption
Depends on:
Amount of alcohol consumed
The alcohol content of
the beverage
Time taken to consume it
Quantity and type of food
present in the stomach
Physiology of the consumer
About 5 percent is excreted
unchanged in breath,
perspiration, and urine
17
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-17
Toxicology of Alcohol
• The analysis of alcohol exemplifies the primary
objective of forensic toxicology—the detection
and isolation of drugs in the body for the
purpose of determining their influence on
human behavior.
• Alcohol, or ethyl alcohol, is a colorless liquid
normally diluted with water and consumed as a
beverage.
• Like any depressant, alcohol principally effects
the central nervous system, particularly the
brain.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-18
Alcohol on the Breath
• A major branch of
forensic toxicology
deals with the
measurement of
alcohol in the body
for matters that
pertain to violations
of criminal law.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
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Alcohol & Circulatory System
• Humans have a closed circulatory system
consisting of a heart, arteries, veins, and
capillaries.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
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Alcohol & Circulatory System
• Alcohol is absorbed from the stomach and
small intestines into the blood stream.
• Alcohol is carried to the liver where the process
of its destruction starts.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-21
Alcohol & Circulatory System
• Blood, carrying alcohol, moves to the heart and
is pumped to the lungs.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-22
Alcohol & Circulatory System
• In the lungs, carbon dioxide and alcohol leave
the blood and oxygen enters the blood in the air
sacs known as alveoli.
• Then the carbon dioxide and alcohol are
exhaled during breathing.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-23
Toxicology of Alcohol
• The analysis of alcohol exemplifies the primary
objective of forensic toxicology—the detection
and isolation of drugs in the body for the
purpose of determining their influence on
human behavior. Video
• Alcohol, or ethyl alcohol, is a colorless liquid
normally diluted with water and consumed as a
beverage.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-24
Breath Testers
• Breath testers that
operate on the
principle of infrared
light absorption are
becoming
increasingly popular
within the law
enforcement
community.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-25
Toxicology of Alcohol
• Like any depressant, alcohol principally effects
the central nervous system, particularly the
brain.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-26
Alcohol Levels
• Then the alcohol concentration slowly
decreases until a zero level is again reached.
• Factors such as time taken to consume the
drink, the alcohol content, the amount
consumed, and food present in the stomach
determine the rate at which alcohol is
absorbed.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-27
Alcohol Levels
• Elimination of alcohol throughout the body is
accomplished through oxidation and excretion.
• Oxidation takes place almost entirely in the
liver, while alcohol is excreted unchanged in
the breath, urine, and perspiration.
• The extent to which an individual may be
under the influence of alcohol is usually
determined by either measuring the quantity of
alcohol present in the blood system or by
measuring the alcohol content in the breath.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-28
Alcohol Levels
• Experimental
evidence has
verified that the
amount of
alcohol exhaled
in the breath is
in direct
proportion to
the blood
concentration.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-29
Alcohol and Law
• The American Medical Association and the
National Safety Council have been able to exert
considerable influence in convincing the states
to establish uniform and reasonable bloodalcohol standards.
• Between 1939 and 1964 a person having a
blood-alcohol level in excess of 0.15 percent w/v
was to be considered under the influence,
which was lowered to 0.10 percent by 1965.
• In 1972 the impairment level was
recommended to be lowered again to 0.08
percent w/v. It remains there today.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-30
Alcohol and Law
• To prevent a person’s refusal to take a test for
alcohol consumption, the National Highway
Traffic Safety Administration recommended an
“implied consent” law.
• Adopted by all states by 1973, this law states
that the operation of a motor vehicle on a
public highway automatically carries with it
the stipulation that a driver will submit for a
test for alcohol intoxication if requested or be
subject to loss of the license.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-31
Breath Testers
• Many types of breath testers are designed to
analyze a set volume of breath.
• The captured breath is exposed to infrared
light.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-32
Breath Testers
• It’s the degree of the interaction of the
light with alcohol in the captured breath
sample that allows the instrument to
measure a blood alcohol concentration
in breath.
• Some breath testing devices also use fuel
cells.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-33
Field Testing
• Law enforcement officers typically use field
sobriety tests to estimate a motorist’s degree of
physical impairment by alcohol and whether or
not an evidential test for alcohol is justified.
• The horizontal gaze nystagmus test, walk and
turn, and the one-leg stand are all considered
reliable and effective psychophysical tests.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-34
Gas Chromatography Testing
• Gas chromatography offers the toxicologist the
most widely used approach for determining
alcohol levels in blood.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-35
Gas Chromatography Testing
• Blood must always be drawn under medically
accepted conditions by a qualified individual.
• It is important that a nonalcoholic disinfectant
be applied before the suspect’s skin is
penetrated with a sterile needle or lancet.
• Once blood is removed from an individual, its
preservation is best ensured when it is sealed in
an airtight container after an anticoagulant
and a preservative have been added and stored
in a refrigerator.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-36
The Confirmation Step
• The GC separates the sample into its
components, while the MS represents a unique
“fingerprint” pattern that can be used for
identification.
• Once the drug is extracted and identified, the
toxicologist may be required to provide an
opinion on the drug’s effect on an individual’s
natural performance or physical state.
FORENSIC SCIENCE: An Introduction, 2nd ed.
By Richard Saferstein
©2011, 2008 Pearson Education, Inc.
Upper Saddle River, NJ 07458
6-37